Dual housing clutch assembly for a hybrid vehicle

ABSTRACT

A clutch assembly for a hybrid vehicle includes a clutch assembly including a first housing comprising a first clutch, a first clutch actuator and a second housing having the first clutch actuator at least partially disposed therein so that said first clutch actuator selectively engages the first clutch.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/140,666, filed on Dec. 24, 2008. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The present invention relates generally to transmissions and, moreparticularly, to a clutch configuration for use in a hybrid transmission

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Internal combustion engines combust an air and fuel mixture withincylinders to drive pistons, which produces drive torque. Air flow intogasoline engines is regulated via a throttle. More specifically, thethrottle adjusts throttle area, which increases or decreases air flowinto the engine. As the throttle area increases, the air flow into theengine increases. A fuel control system adjusts the rate that fuel isinjected to provide a desired air/fuel mixture to the cylinders.Increasing the amount of air and fuel provided to the cylindersincreases the torque output of the engine.

Hybrid vehicles are increasing in popularity. Hybrid vehicles generallyhave two power sources. The internal combustion engine is a first powersource and an electric motor is a second power source. The electricmotor is used as a power source in city driving where vehicle kineticenergy can be recovered by regenerative braking, converted to electricand chemical form, and stored in a battery, from which the motor isdriven. The internal combustion engine is most suitable in highwaydriving, during which wheel braking and opportunities for energyrecovery are infrequent, and the engine operates at its greatestefficiency.

In mixed driving conditions, the electric motor and combustion enginemay be used together to transmit power to a transmission input shaft,depending on driving conditions and the magnitude of the batterycapacity.

Typically, an engine includes a separate starter motor used for startingthe engine when the engine is stopped. Reducing the amount of componentsin a vehicle reduces the vehicle weight and, therefore, increases theoverall range or gas mileage of the vehicle.

SUMMARY

The present disclosure eliminates a conventional starter motor from thevehicle and uses the hybrid electric motor and actuators to start theengine of the vehicle.

In one aspect of the disclosure, a clutch assembly includes a clutchassembly including a first housing comprising a first clutch, a firstclutch actuator and a second housing having the first clutch actuator atleast partially disposed therein so that said first clutch actuatorselectively engages the first clutch.

The clutch assembly may be incorporated into a transmission having atleast one electric motor therein. The motors may be used to operate ahybrid electric vehicle.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples areintended for purposes of illustration only and are not intended to limitthe scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an exemplary engine systemaccording to the principles of the present disclosure;

FIG. 2 is a block diagrammatic view of a hybrid vehicle system;

FIG. 3 is an end view of a transmission according to the presentdisclosure;

FIG. 4 is a cutaway view of a transmission wherein the transmission isin the off state and the transmission is starting the engine;

FIG. 5 is a cutaway view of a transmission for the clutch positionsafter starting of the vehicle;

FIG. 6 is a cross-sectional view of a secondary housing according to thepresent disclosure; and

FIG. 7 is a flowchart of a method for starting a hybrid vehicle usingthe hybrid transmission.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is in no wayintended to limit the disclosure, its application, or uses. For purposesof clarity, the same reference numbers will be used in the drawings toidentify similar elements. As used herein, the phrase at least one of A,B, and C should be construed to mean a logical (A or B or C), using anon-exclusive logical or. It should be understood that steps within amethod may be executed in different order without altering theprinciples of the present disclosure.

As used herein, the term module refers to an Application SpecificIntegrated Circuit (ASIC), an electronic circuit, a processor (shared,dedicated, or group) and memory that execute one or more software orfirmware programs, a combinational logic circuit, and/or other suitablecomponents that provide the described functionality.

Referring now to FIG. 1, a functional block diagram of an exemplaryengine system 100 is presented. The engine system 100 includes an engine102 that combusts an air/fuel mixture to produce drive torque for avehicle based on a driver input module 104. Air is drawn into an intakemanifold 110 through a throttle valve 112. For example only, thethrottle valve 112 may include a butterfly valve having a rotatableblade. An engine control module (ECM) 114 controls a throttle actuatormodule 116, which regulates opening of the throttle valve 112 to controlthe amount of air drawn into the intake manifold 110.

Air from the intake manifold 110 is drawn into cylinders of the engine102. While the engine 102 may include multiple cylinders, forillustration purposes a single representative cylinder 118 is shown. Forexample only, the engine 102 may include 2, 3, 4, 5, 6, 8, 10, and/or 12cylinders. The ECM 114 may instruct a cylinder actuator module 120 toselectively deactivate some of the cylinders, which may improve fueleconomy under certain engine operating conditions.

Air from the intake manifold 110 is drawn into the cylinder 118 throughan intake valve 122. The ECM 114 controls a fuel actuator module 124,which regulates fuel injection to achieve a desired air/fuel ratio. Fuelmay be injected into the intake manifold 110 at a central location or atmultiple locations, such as near the intake valve of each of thecylinders. In various implementations not depicted in FIG. 1, fuel maybe injected directly into the cylinders or into mixing chambersassociated with the cylinders. The fuel actuator module 124 may haltinjection of fuel to cylinders that are deactivated.

The injected fuel mixes with air and creates an air/fuel mixture in thecylinder 118. A piston (not shown) within the cylinder 118 compressesthe air/fuel mixture. Based upon a signal from the ECM 114, a sparkactuator module 126 energizes a spark plug 128 in the cylinder 118,which ignites the air/fuel mixture. The timing of the spark may bespecified relative to the time when the piston is at its topmostposition, referred to as top dead center (TDC).

The combustion of the air/fuel mixture drives the piston down, therebydriving a rotating crankshaft (not shown). The piston then begins movingup again and expels the byproducts of combustion through an exhaustvalve 130. The byproducts of combustion are exhausted from the vehiclevia an exhaust system 134.

The spark actuator module 126 may be controlled by a timing signalindicating how far before or after TDC the spark should be provided.Operation of the spark actuator module 126 may therefore be synchronizedwith crankshaft rotation. In various implementations, the spark actuatormodule 126 may halt provision of spark to deactivated cylinders.

The intake valve 122 may be controlled by an intake camshaft 140, whilethe exhaust valve 130 may be controlled by an exhaust camshaft 142. Invarious implementations, multiple intake camshafts may control multipleintake valves per cylinder and/or may control the intake valves ofmultiple banks of cylinders. Similarly, multiple exhaust camshafts maycontrol multiple exhaust valves per cylinder and/or may control exhaustvalves for multiple banks of cylinders. The cylinder actuator module 120may deactivate the cylinder 118 by disabling opening of the intake valve122 and/or the exhaust valve 130.

The time at which the intake valve 122 is opened may be varied withrespect to piston TDC by an intake cam phaser 148. The time at which theexhaust valve 130 is opened may be varied with respect to piston TDC byan exhaust cam phaser 150. A phaser actuator module 158 controls theintake cam phaser 148 and the exhaust cam phaser 150 based on signalsfrom the ECM 114. When implemented, variable valve lift may also becontrolled by the phaser actuator module 158.

The engine system 100 may include a boost device that providespressurized air to the intake manifold 110. For example, FIG. 1 shows aturbocharger 160 that includes a hot turbine 160-1 that is powered byhot exhaust gases flowing through the exhaust system 134. Theturbocharger 160 also includes a cold air compressor 160-2, driven bythe turbine 160-1, that compresses air leading into the throttle valve112. In various implementations, a supercharger, driven by thecrankshaft, may compress air from the throttle valve 112 and deliver thecompressed air to the intake manifold 110.

A waste gate 162 may allow exhaust gas to bypass the turbocharger 160,thereby reducing the boost (the amount of intake air compression) of theturbocharger 160. The ECM 114 controls the turbocharger 160 via a boostactuator module 164. The boost actuator module 164 may modulate theboost of the turbocharger 160 by controlling the position of the wastegate 162. In various implementations, multiple turbochargers may becontrolled by the boost actuator module 164. The turbocharger 160 mayhave variable geometry, which may be controlled by the boost actuatormodule 164.

An intercooler (not shown) may dissipate some of the compressed aircharge's heat, which is generated as the air is compressed. Thecompressed air charge may also have absorbed heat because of the air'sproximity to the exhaust system 134. Although shown separated forpurposes of illustration, the turbine 160-1 and the compressor 160-2 areoften attached to each other, placing intake air in close proximity tohot exhaust.

The engine system 100 may include an exhaust gas recirculation (EGR)valve 170, which selectively redirects exhaust gas back to the intakemanifold 110. The EGR valve 170 may be located upstream of theturbocharger 160. The EGR valve 170 may be controlled by an EGR actuatormodule 172.

The engine system 100 may measure the speed of the crankshaft inrevolutions per minute (RPM) using an RPM sensor 180. The temperature ofthe engine coolant may be measured using an engine coolant temperature(ECT) sensor 182. The ECT sensor 182 may be located within the engine102 or at other locations where the coolant is circulated, such as aradiator (not shown).

The pressure within the intake manifold 110 may be measured using amanifold absolute pressure (MAP) sensor 184. In various implementations,engine vacuum, which is the difference between ambient air pressure andthe pressure within the intake manifold 110, may be measured. The massflow rate of air flowing into the intake manifold 110 may be measuredusing a mass air flow (MAF) sensor 186. In various implementations, theMAF sensor 186 may be located in a housing that also includes thethrottle valve 112.

The throttle actuator module 116 may monitor the position of thethrottle valve 112 using one or more throttle position sensors (TPS)190. The ambient temperature of air being drawn into the engine 102 maybe measured using an intake air temperature (IAT) sensor 192. The ECM114 may use signals from the sensors to make control decisions for theengine system 100.

The ECM 114 may communicate with a transmission control module 194 tocoordinate shifting gears in a transmission (not shown). For example,the ECM 114 may reduce engine torque during a gear shift. The ECM 114may communicate with a hybrid control module 196 to coordinate operationof the engine 102 and an electric motor 198. The hybrid control module196 may control for fuel economy or performance. The vehicle operatormay be able to select the mode of operation.

The electric motor 198 may also function as a generator, and may be usedto produce electrical energy for use by vehicle electrical systemsand/or for storage in a battery. In various implementations, variousfunctions of the ECM 114, the transmission control module 194, and thehybrid control module 196 may be integrated into one or more modules.

An electronic brake control module 200 may also communicate with theengine control module 114. Various torques associated with theelectronic braking system may be factored into the torque control aswill be described below.

Each system that varies an engine parameter may be referred to as anactuator that receives an actuator value. For example, the throttleactuator module 116 may be referred to as an actuator and the throttleopening area may be referred to as the actuator value. In the example ofFIG. 1, the throttle actuator module 116 achieves the throttle openingarea by adjusting the angle of the blade of the throttle valve 112.

Similarly, the spark actuator module 126 may be referred to as anactuator, while the corresponding actuator value may be the amount ofspark advance relative to cylinder TDC. Other actuators may include theboost actuator module 164, the EGR actuator module 172, the phaseractuator module 158, the fuel actuator module 124, and the cylinderactuator module 120. For these actuators, the actuator values maycorrespond to boost pressure, EGR valve opening area, intake and exhaustcam phaser angles, fueling rate, and number of cylinders activated,respectively. The ECM 114 may control actuator values in order togenerate a desired torque from the engine 102.

Referring now to FIG. 2, a general block diagrammatic view of a hybridvehicle 210 is illustrated. The vehicle includes the engine system 100that includes a crankshaft 212 that is in communication with a hybridtransmission system 214. The hybrid transmission system 214 communicatestorque to the wheels of a vehicle through a driveline 216.

The hybrid transmission system 214 includes at least one electric motor220, actuators 222, which may include clutches or the like for engagingand disengaging gears within a transmission 230. Both the transmissioncontrol module 194 and the hybrid control module 196 may be usedtogether to control the hybrid transmission system 214. The transmissioncontrol module 194 and the hybrid control module 196 are shown asseparate elements in FIGS. 1 and 2. However, the two may be combined asa single control module 240.

Referring now to FIG. 3, an end view of a transmission having a mainhousing 310 and a plurality of secondary housing 312A, 312B, and 312C.As will be described below, the secondary housings are used forstationary piston assemblies. Three secondary housings are illustrated.However, various members of housings may be provided.

Referring now to FIG. 4, a cutaway view of the hybrid transmission 214is illustrated. Components of the transmission include a flywheel damperassembly 400 that attaches the transmission to the engine and atransmission portion 402 that includes gears for changing the driveratio of the transmission. The clutch assembly portion 404 isillustrated in further details. The transmission 214 has a firstelectric motor 220A and a second electric motor 220B. The motor 220Aincludes a stator 410A and a rotor 412A. Motor 220B includes a stator410B and a rotor 412B. The hybrid transmission system 214 also includesa first planetary gear set 414A that includes a ring gear 416A, a sungear 418A and planetary gears 420A. The gear set 414A is incommunication with the transmission shaft 430 through various supportcomponents 432.

A second gear set 414B is provided for communicating torque between theelectric motor 220B and the transmission shaft 430. The second gear setmay also be a planetary gear set that includes a ring gear 416B, a sungear 418B and planetary gears 420B. The operation of the gear sets 414Aand 414B will be further described below.

The hybrid transmission system 214 includes a first clutch assembly 440and a second clutch assembly 442. The first clutch assembly 440 is usedfor both starting the engine 100 of FIG. 2 and for operating thetransmission. The clutch assembly 442 is also used for operating thetransmission. The first clutch assembly 440 includes a spring 444 thatacts upon an actuator or piston 446. The spring 444 pushes the piston446 away from a clutch pack 448. This is the at-rest position. Theclutch pack 448 has disks coupled to a clutch housing 450 and disks 452in communication with a clutch support 454. The secondary housing 312Aincludes a pressure port 456 for providing pressure into a cavity formedbetween the piston 446 and the piston cavity 458. The piston 446 isillustrated in a retracted at-rest position so the cavity is notpresent. The cavity will be illustrated below in FIG. 5. A seal 460seals the piston to the cavity 458. When hydraulically charged thepiston 446 is moved.

A second piston assembly 470 is illustrated. The second piston assembly470 includes a spring 472 disposed within a piston cavity 474. Thepiston cavity 474 also includes a spring cavity 476. The piston cavity474 includes a fluid port 478 for providing hydraulic fluid into apiston chamber 480 formed between a first piston 482 and a second piston484. A first seal 486 disposed on the first piston 482 forms a sealwithin the piston cavity 474. A second seal 488 fluidically seals thepiston chamber 480 and the piston 484 between the first piston 482 andthe outer wall of the piston cavity 474. The piston 484 is preventedfrom moving axially toward the motor B by a stop 492.

The spring 472 biases the piston 482 axially to engage the disks 448 and452. Extension of the spring and thus the housing is an at-restcondition. As will be described below, engagement of the clutch disks448 and 452 ultimately allow the gear assembly 414B to provide astarting torque to the engine. Also, the gear assembly 414A alsoprovides an electric starting torque to the transmission shaft 430 forproviding starting torque to the engine. The second clutch assembly 442also includes disks 502 and 504 used for engaging and disengagingvarious gears in the gear set 414B to provide various drive ratios in aconventional manner. The hydraulically charged position of the piston isaway from the clutch.

Referring now to FIG. 5, the piston assembly 470 is illustrated in aretracted position. That is, the piston 482 is retracted from the disks448. In this embodiment, the piston 486 is retracted axially towardsmotor 410A by providing hydraulic fluid through the port 478. As thehydraulic fluid chamber 480 expands due to the hydraulic forces therein,the force of the spring 472 is overcome and thus the clutch is in anormal operating position.

The piston 446 is thus allowed to operate the clutch assembly 440 bymoving the piston 446 so that the clutch disks 448, 452 engage. Theoperation of the clutch assemblies 440 and 442 allow various driveratios to be provided by the transmission shaft 430.

In operation, when the engine of the vehicle is not started, the spring472 pushes the piston 482 into engagement so that the clutch disks 448and 452 have sufficient friction therebetween. By fixing the clutchsupport 454 in place, the ring gear 416B is also fixed into position.The sun gear 418B is driven by the motor B and thus torque is providedto the transmission shaft 430. The motor A drives the sun gear 418A sothat torque is transmitted to the transmission shaft 430. The torqueprovided by the motor 220A and motor 220B provides a sufficient amountof torque to start the engine system 100 illustrated in FIG. 2. Thehybrid transmission system 214 ultimately couples the transmission shaft430 to the crankshaft 212 of the engine system 100.

After the engine 100 is started, hydraulic fluid is provided through theport 478 to provide a sufficient hydraulic pressure between the pistons482 and 484 to overcome the force of the spring 472 and thus allow thepiston 482 to disengage the disks 448, 452. The clutches 440 and 442thereafter are allowed to operate the transmission and the gearing in adesired manner.

A third piston assembly 510 is illustrated having a spring 512 thatpushes pistons 514 and 516 apart. Hydraulic fluid enters a chamberthrough a port 518 to move the piston 516 into engagement with theclutch assembly 442. The piston 514 remains stationary while the piston516 moves axially.

Referring now to FIG. 6, a side view of the secondary housing 312 isillustrated in further detail. This view is provided to illustrate therelative positions of the first piston cavity 458 and the second pistoncavity 474. The housing 312 may be located using dowel pins or otherlocating methods. The dowel pins may be located on the main housing 310or the secondary housing 312. The dowel pins, not shown, transfer thetorque and the thrust load created when the clutch is applied. Byproviding the clutch assembly illustrated, increased clutch capacitywith the same transmission boundary conditions may be provided. Also, areduced number of clutch plates or disks are provided in the clutchpacks 440 and 442. Spin loss is also reduced while increasing the fuelefficiency of the vehicle. Also, the additional housing allows threepistons to be stacked radially decreasing the transmission length.

Referring now to FIG. 7, a method for operating a hybrid vehicle is setforth. In step 610, the vehicle is not in use, meaning that the engineis not started. In step 612, the first piston is biased with a firstspring torque force to engage the first clutch against a first clutchpack. This essentially prevents the clutch support 454 from moving. Asufficient spring force is provided to prevent the clutch support frommoving and therefore the second motor is in communication with thetransmission shaft 430 of FIGS. 4 and 5. Thus, the at-rest position iswith the clutch engaged. In step 614, the vehicle is started with thefirst spring force engaging the disks 448, 452 of the first clutch 440.In step 616, when the vehicle is not started, step 614 is againperformed in which the first spring force is engaged with the firstclutch. When the vehicle is started in step 616, step 618 generateshydraulic pressure to overcome the first spring force. The hydraulicpressure is provided between the first piston 482 and the second piston484 into the hydraulic chamber 480. Enough hydraulic fluid is providedto overcome the spring force and thus retract the piston 482 fromengagement with the clutch disks so that the clutch disks 448 and 452 ofFIGS. 4 and 5 turn freely. This disengagement of the clutch is performedin step 620.

In step 622, the transmission is operated in a normal manner. That is,the piston 446 engages and disengages the first clutch 440 and thesecond piston 516 engages and disengages the clutch assembly 442. Bycontrolling the clutches in a conventional manner, the gear ratio of thetransmission shaft 430 may be changed relative to an input shaft of thetransmission.

The broad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, the specification, and the following claims.

1. A clutch assembly comprising: a first housing; a first clutchdisposed within the first housing; a first clutch actuator; a secondhousing having the first clutch actuator at least partially disposedtherein so that said first clutch actuator selectively engages the firstclutch; and a second clutch actuator disposed at least partially withinthe second housing so that said second clutch actuator selectivelyengages the first clutch, wherein the first clutch actuator and thesecond clutch actuator engage the first clutch by contacting the firstclutch independent from one another.
 2. A clutch assembly as recited inclaim 1 wherein the first clutch actuator comprises a first piston and afirst spring, said first spring biasing the first piston toward thefirst clutch and wherein the second clutch actuator comprise a secondspring and a second piston, said second spring biasing the second pistonaway from the first clutch.
 3. A clutch assembly as recited in claim 2wherein the second piston is hydraulically biased toward the firstclutch.
 4. A clutch assembly as recited in claim 1 further comprising asecond clutch disposed within the first housing and a third clutchactuator disposed within the second housing.
 5. A clutch assembly asrecited in claim 4 wherein the first clutch actuator, the second clutchactuator and the third clutch actuator are radially disposed.
 6. Aclutch assembly as recited in claim 1 wherein the first actuatorcomprises a first spring, said first spring biasing the first clutchactuator toward said first clutch.
 7. A clutch assembly as recited inclaim 1 wherein the first clutch actuator comprises a first piston and afirst spring, said first spring biasing the first piston toward thefirst clutch.
 8. A clutch assembly as recited in claim 7 wherein thesecond housing comprises a first piston cavity having a spring cavitytherein, and the first spring is disposed within the spring cavity.
 9. Aclutch assembly as recited in claim 7 wherein the first piston and thesecond housing at least partially form a piston chamber that selectivelyhydraulically biases the first piston away from the first clutch.
 10. Aclutch assembly as recited in claim 9 further comprising a secondpiston, wherein said piston chamber is disposed between the first pistonand the second piston.
 11. A transmission assembly comprising: a clutchassembly as recited in claim 1; a transmission shaft; and a plurality ofgears selectively coupled to the shaft by the clutch assembly.
 12. Atransmission assembly as recited in claim 11 further comprising: a firstelectric motor; and a second electric motor.
 13. A transmission assemblyas recited in claim 12 wherein the clutch assembly is disposed axiallybetween the first electric motor and the second electric motor.
 14. Atransmission assembly as recited in claim 12 wherein the first electricmotor is disposed within the first housing and the second electric motoris disposed within the first housing.
 15. A hybrid vehicle comprising:an engine; and the transmission of claim 12 disposed within the firsthousing.
 16. A hybrid vehicle as recited in claim 15 wherein the firstclutch actuator comprises a first spring, said first spring biasing thefirst clutch actuator toward said first clutch to start the engine. 17.A hybrid vehicle as recited in claim 16 wherein the first clutchactuator is hydraulically biased away from the first clutch after theengine started.
 18. A transmission assembly comprising: a primaryhousing comprising a first clutch; a first electric motor disposedwithin the primary housing; a second electric motor disposed within theprimary housing; a plurality of secondary housings; and a plurality ofstarting clutch actuators each disposed at least partially within arespective one of the plurality of secondary housings, said plurality ofstarting clutch actuators selectively engaging the first clutch bycontacting the first clutch independent from one another.
 19. Atransmission assembly as recited in claim 18 further comprising aplurality of transmission control actuators each disposed at leastpartially with a respective one of the plurality of secondary housings.